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Friday, 14 March 2014

How do you make a monster gun disappear?

In the second half of the 19th Century advances
in metallurgy allowed an unprecedented increase in the size and weight of
artillery pieces for applications in which mobility by land was not a concern.
This applied to weapons mounted either in fixed fortifications, or on ships. The
speed of development was amazing. In the early 1860s the heaviest weapon afloat
was the 68-pounder muzzle-loading cannon, an oversize version of the guns
carried by Nelson’s Victory six
decades earlier. It weighed some four tons, and was standard armament even on ships
which were revolutionary in themselves, such as HMS Warrior. By 1867 however 11-inch and 12-inch weapons of 25 tons
were coming into service, firing 600-pound projectiles and yet larger weapons
were to follow in the coming years.

These guns had a slow rate of fire and protecting them
against enemy fire during their laborious loading sequences was a vital
concern. One obvious solution was to place them behind protective barriers –
earth or masonry fortifications on land, armour at sea. An additional
protection was however to expose them to enemy view for the shortest possible
time so that they would be visible only in the brief interval of firing, returning
to cover immediately thereafter.

The solution to this was “the disappearing mount”. The gun-barrel
was mounted on hinged arms which, when in the lowered position, supported it in
a horizontal position behind a protective barrier, invisible to an observer
outside it. In this position it could be loaded in safety, the short range
capabilities of the period precluding plunging fire, and when ready the hinged
arms would carry the barrel up above the barrier. It would remain exposed only
until fired. Its recoil would sweep the weapon back down to the loading
position again, braked by a counterweight which in due course would be used to
hoist the gun for the next firing. In later years hydraulic systems were used
to supplement, or replace, the counterweight.

The system saw only limited use at sea – as discussed later –
but it reached its highest level of sophistication in land fortifications, some
such weapons remaining in use up to WW2. The principle is best illustrated by reference
to a land-based weapon, shown in the photographs below. Taken around 1905,
these show a French “Canet” weapon of 9.4-inch calibre under test, before being
disassembled and hereafter reassembled in a coast-defence fortress. The large
circular disc is an armoured shield which will lie flush with the top of a concrete
pit and has a rectangular opening in the top through which the gun-barrel will
emerge. The first photograph shows the weapon in its lowered position, ready
for loading, while in the second the gun has been raised to the firing
position. The entire assembly, including the top shield, could be rotated through
for aiming.

Canet 9.4-inch weapon in lowered position (1905)The unit will later be located in a circular concrete pitThe circular armoured roof will lie flush with the surrounding ground

Details of the hinging system varied from one design to another,
and hydraulics were increasingly used not just to manage the forces involved,
but to allow accurate adjustments in azimuth and elevation and to facilitate
loading. The illustration below shows an American 12-inch mounting of mid-1890s
vintage. Similar mounting were used for 14-inch guns in American coastal
fortification from the early 1900s and two 16-inch weapons which were employed
to defend the Panama Canal until at the end of WW2.

Use at sea of disappearing mountings was of much shorter
duration. The mechanisms involved were complex and operation was not helped by ship’s
rolling and pitching. The Royal Navy only employed such mountings on a single
capital ship, HMS Temeraire, launched
in 1876. Four 11-inch 25-ton guns weapons were carried on Moncrieff mountings
(so called after their inventor), two forward, two aft, in pear-shaped armoured
redoubts. The layout can be seen below and it will also be noted that Temeraire also had 10-inch weapons mounted
amidships inside an armoured central
battery. The experiment of using disappearing mounts was not repeated in any
Royal Naval capital ship due to the weight and space demands – the latter being
obvious from the drawing.

HMS Temeraire at sea, the forward mounting just visibleShe was the largest brig ever built and, not surprisingly, slow under sail

An unusual use of a ship-mounted disappearing mount for
heavy guns was in the bizarre, circular, Russian Popovka-type
coast defence ships. Readers of my novel “Britannia’sWolf” will already have made an acquaintance with these monsters and a dual
12-inch mounting can be seen below on a Popovka
inside its encircling armoured wall.

12-inch guns on disappearing mountings on a Russian Popovka

The other main application of disappearing mounts was in “Flatiron”
gunboats, also called Rendels after their inventor. These were small
shallow-draught vessels, very manoeuvrable, and carrying a single enormous gun,
usually in the 8-inch to 12-inch range. This was fixed to fire forward along the
craft’s axis and was aimed by aiming the entire vessel. In their heyday, from
about 1867 to 1880, more than 40 were built for the Royal Navy, including
Australian units, and large numbers by most other navies, including minor ones.
They were seen primarily as coast and estuary-defence vessels and were expected
to operate in groups. As such their role was superseded by the arrival of the fast
torpedo boat and they were quickly relegated to other duties. Several Rendel
designs, including the 20-unit Ant
class for the Royal Navy, employed disappearing mountings.

A Rendel unit with a sophisticated
hydraulically-operated disappearing mount - the fictional HMS Toad, originally ordered from a British yard by the
Greek Navy, but taken over by the Royal Navy when Greece could not pay for her –
plays a central role in my novel “Britannia’s Reach”. As such the Toad is almost a character in her own right.

The Imperial Chinese navy also made extensive use of
Rendels, some participating in the Sino-French War of 1884 (2 lost) and in the Sino-Japanese
War of 1895 (12 sunk or captured). Almost all were constructed in Britain and
carried sailing rig – as in the illustrations below – during the delivery
voyage but are likely to have dispensed with it in normal service.

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About Me

My "Dawlish Chronicles" are set in the late 19th Century and reflect my deep interest in the politics, attitudes and technology of the period. The fifth novel in the series, “Britannia’s Amazon” is now available in both paperback and Kindle formats. It follows the four earlier Dawlish Chronicles, "Britannia's Wolf", "Britannia's Reach”, "Britannia's Shark" and "Britannia's Spartan". Click on the book covers below to learn more or to purchase.
I’ve had an adventurous career in the international energy industry and am proud of having worked in every continent except Antarctica. History is a driving passion in my life and I have travelled widely to visit sites of historical significance, many insights gained in this way being reflected in my writing. I welcome contact on Facebook and via this Blog. My website is www.dawlishchronicles.com and its “Conflict” section has a large number of articles on topics from the mid-18th Century to the early 20th Century.